Yaesu ft290r I have recently purchased a second hand yaesu ft-290r mk 1 I had to replace the 1.5amp fuse (blown) it powers up, has tx, but no tx audio. rx hiss but no audio. also the previous owner suspects reverse polarity of the power lead ? what can be wrong , and is it repairable THANKYOU.

SOURCE: Yaesu FT-727R

Hi,

The Yaesu FT727R does not have any internal fuse that I know of. Straight from the Battery + terminal it goes to the on/off switch (that is coupled to the volume control). From the switch it goes to circuitry (PCB). Incidentally, it is the battery that normally has a thermal switch/fuse that cuts off when a certain temperature is reached (when charging).

Other than check the battery terminals/contacts for corrosion and do a little abrasive cleaning, am afraid you'll have to open the unit for a look and see. Should you be interested, a schematic diagram is available here.

Good luck and kind regards.

SOURCE: cobra 29ltd classic : no rx / tx

Hi,

D23 is the reverse protection diode and it shorting is the primary reason your fuse blew. As you posted, power was applied in reverse, hence other components would also fail. Pls check:
1. D22 - 9.1V Zener Diode
2. TR23 (2SC1096) 9 Volts regulator
3. D19 - 5.1 Zener Diode
4. IC4 (TA7222) - Audio Amp
5. TR14 (2SC2029B/10) - Finals
6. TR15 (2SC2028B/20) - Driver
7. Most capacitors over 220uF (like C123, C114 & C112)

Hope that this be of help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

SOURCE: Yaesu FT-50R battery drain

I have the same radio.

Does the radio work? Could it be the battery that's getting hot?


Geno

N8BHG

Patrick Patterson

• 109 Answers
• Posted on Aug 21, 2008

SOURCE: VX-1 Service Manual

this address should help you out http://www.ham.dmz.ro/yaesu/vx-1r-ext-mic-diagrams.php
as for the service manual you will have to order that from yaesu or see if the local Ham radio sevice shop has an extra one they will sell.

SOURCE: Yaesu Ft-50 hard to turn on

The rubber power button is impregnated with carbon and when pressed, it makes contact with two points on the printed circuit board, turning on the radio. This button eventually wears out and needs to be replaced, which is a rather easy process.

I've performed the operation four times - takes about 15 minutes. The button is available from Yaesu.

I also tried "repair kits" for these buttons which are supposed to replace the conductive surface. Both times, they failed again within a couple of weeks.

The upside is the new button is not as quite as tall as the original and requires depressing it below the surface of the case to switch, which prevents accidently turning off the radio.

Good luck, and 73

DE NøAWN